Chapter 9
Wastewater Treatment
As civilization developed and cities grew, domestic sewage and industrial waste were
eventually discharged into drainage ditches and sewers, and the entire contents emptied
into the nearest watercourse. For major cities, this discharge was often enough to
destroy even a large body of water. As Samuel Taylor Coleridge described the city of
Cologne (Koln) in Germany:In Kiiln, a town of monks and bones,
And pavements fang’d with murderous stones,
And rags and hags, and hideous wenches,
I counted two-and-seventy stenches
All well defined, and several stinks!
Ye Nymphs that reign o’er sewers and sinks,
The river Rhine, it is well known,
Doth wash your city of Cologne;
But tell me Nymphs! what power divine
Shall henceforth wash the river Rhine?During the nineteenth century, the River Thames was so grossly polluted that
the House of Commons stuffed rags soaked with lye into cracks in the windows of
Parliament to reduce the stench.
Sanitary engineering technology for treating wastewater to reduce its impact on
watercourses, pioneered in the United States and England, eventually became eco-
nomically, socially, and politically feasible. This chapter reviews these systems from
the earliest simple treatment systems to the advanced systems used today. The discus-
sion begins by reviewing those wastewater characteristics that make disposal difficult,
showing why wastewater cannot always be disposed of on-site, and demonstrating the
necessity of sewers and centralized treatment plants.
WASTEWATER CHARACTERISTICS
Discharges into a sanitary sewerage system consist of domestic wastewater, industrial
discharge, and infiltration. The last adds to the total wastewater volume but is not itself
a concern in wastewater disposal, infiltration will even dilute municipal sewage to
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